Michael Schumacher's medical records have been stolen and offered for sale.

The seven-time Formula One racing champion only came out of a coma last week after suffering severe head injuries in a ski accident during the Christmas holidays last year.

The German's spokesperson, Sabine Kehm, issued a brief statement this morning (NZ time) stating they were aware of the theft but could not verify if the documents were authentic.

"For several days stolen documents and data are being offered for sale. The offerer claims them to be the medical file of Michael Schumacher.

"We cannot judge if these documents are authentic. However, the documents are clearly stolen. The theft has been reported. The authorities are involved."

Both the purchase and publication of the documents was illegal as the contents of medical files were private and confidential, Kehm said.

"We will therefore, in every single case, press for criminal charges and damages against any publication of the content or reference to the medical file."

Schumacher faces a long recovery following such a prolonged period of time in a coma.

Last week he was transferred to Lausanne Hospital in Switzerland for rehabilitation.

Professor Simone Di Giovanni, an expert in restorative neuroscience at Imperial College London, last week said it was very difficult to predict recovery in people emerging from a coma.

"That can range from someone who merely opens their eyes and may be able to respond to verbal input, to someone who opens their eyes and moves their hands in response to painful input, to someone who interacts with their environment fully and uses language and maybe can have a simple conversation," he said.

"In this case, nobody - with the exclusion of the doctors who are treating Michael Schumacher - knows exactly what the condition of the patient is."

Schumacher, 45, won a record 91 Grand Prix victories before retiring in 2006. He made a brief comeback with Mercedes, but finally stopped racing last year.